Feature Request - Log level CLI Option on pact-stub-service

[YOU54F]

Ola,

We have just switched over to the pact-stub-service, and noticed that we cannot control the log levels.

I am currently outputting the log to a file, tailing the file, with a grep pattern to search for errors.

Would be good to implement this for the pact-stub-server, as per #91

Many thanks in advance!

[YOU54F]

This is the commit that brought in the logging for pact-mock-service

cf84a34

If I get some spare time, I will try and pop a PR in